alt Hacker NewsJust to be a pedant, and because this fact tends to surprise people, asphalt is concrete.
Concrete is a generally defined as any mineral aggregate (so rocks and stones) mixed with a binder (normally cement, but bitumen in the case of asphalt).
As for why roads are normally made out of “normal” concrete, it’s very expensive to build roads like that. Pavements are cheaper to build out of concrete because they only carry the weight of pedestrians, not lots of rolling vehicles. You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension. Asphalt concrete cheats by being flexible, so minor imperfections in the surface or sub-base don’t become sources of critical failures (although they can become pot holes). Asphalt is also cheaper and easier to patch repair, but doesn’t last as long as proper cement road surfaces.
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Possibly. But I noticed offhand in the DFW, Texas area there many local streets - sometimes flat ground-level parking lots - paved entirely in concrete, not just highways. Apparently for them the up front investment in "normal" (portland?) concrete is more economical.
> You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension.
A lot of states use JPCP now for highways that doesn’t require rebar.
To be even more of a pedant, because asphalt is a subset concrete, any comparison between asphalt and concrete is automatically implied as a comparison between asphalt and non-asphalt concrete, and to specify would be redundant.
It's just like when saying "man vs animal", everyone knows that man is a type of animal, but it's implied that it's "man vs non-man animal".